| 摘要 |
PURPOSE:To improve the corrosion resistance of the optical disk by forming a protective film in an outer peripheral part so as to wrap the film up to the rear surface of a substrate. CONSTITUTION:The magneto-optical disk is produced by the following procedures: Thin-film layers 2 consisting of a transparent film 4 for optical interference, a perpendicularly magnetized film 5 and a metallic reflection film 6 are formed on the substrate 1 made of a resin. Since an outer peripheral mask is not used at this time, the thin-film layers 2 infiltrate to the outer peripheral flank 8 of the substrate 1. After a silicone resin is applied on the substrate 1, the substrate is rested at room temp. to cure the resin and to form the protective film 3. The protective film 3 infiltrates to the rear surface of the substrate 1 in the outer peripheral part at this time. Changes in defect rate of the magneto-optical disk produced in such a manner and the conventional magnetooptical disk are investigated by spending about 1000 hours in environmental tests at 80 deg.C and 90%RH. The results, then, reveal that while the defect rate of the latter increases to 26.2 times, the defect rate of the former is 1.2 times and hardly increases and that the former is greatly improved in corrosion resistance as compared with the latter. |
